1. Field of the Invention
The invention relates to an upsetting tool for forming continuous cast slab in upsetting presses with at least one upsetting surface positioned at a slant to the transport direction of the slab and an upsetting surface positioned parallel to the transport direction of the slab and to its longitudinal side surfaces, wherein the upsetting surfaces adjoin one another at a slant angle xcex1, respectively.
2. Description of the Related Art
Upsetting presses serve for reducing the width of rolled goods, in particular, the slab width in hot-rolled wide strip blooming trains. The upsetting presses have for this purpose on both sides of the slab edges pressing tools that are facing one another.
An upsetting press of the aforementioned configuration is known, for example, from European patent application 0 112 516 and comprises a pair of pressing tools which are arranged on both wide sides of a slab blooming train such that their pressing surfaces provided for pressing the slab face one another. One of these pressing surfaces is substantially parallel to the slab advancing direction, the other pressing surface has a surface that is slanted relative to the slab advancing direction.
A vibration unit causes the pressing tool and its parallel and slanted surfaces to vibrate. This known upsetting press comprises moreover a width control unit for controlling the position of the pressing tool in the slab width direction and a control which detects whether the front end of the slab is arranged between the parallel surfaces of the pressing tool and which then actuates the width control device as well as the vibration unit after a certain pressing action has been performed.
From European patent 0 400 385 a flying upsetting press for reduction of the width of slab in hot-rolled wide strip blooming trains is known. The pressing tools required for width reduction of the slab are secured on a tool holder. A crank gear is provided to realize the reduction drive of the pressing tool. The crank gear acts on a guide rod system which is movable in the direction of reduction. The crank gear is arranged in a crank housing which is adjustably arranged in a horizontal press stand. An advancing drive engages the tool holder and acts essentially in the direction of slab advancement. When the advancing drive is not actuated, this known upsetting press can be operated by stop and go operation. The construction of this upsetting press has been proven successful in practice.
From German patent document 196 00 477 A1 an upsetting tool for forming continuous cast slab in slab upsetting presses is known. The upsetting forming surface of this upsetting tool is comprised of several forming surfaces which extended a slant relative to the transport direction of the slab and a further upsetting forming surface which extends parallel to the longitudinal sides of the slab. In the feeding direction of the slab into the upsetting press the slant angle xcex1 of the upsetting forming surface is approximately 19 to 20 degrees. The successively arranged three transitional upsetting forming surfaces have a slant angle of approximately 0.9 to 10 degrees and the exit surface of the upsetting tool has a slant angle xcex2 of 12 degrees. With such upsetting tools it is achieved that the slab material during upsetting flows better toward the center of the slab and that, despite a width upsetting of approximately 300 mm, a cross-section of the upset slab is produced which can be called approximately rectangular.
From German patent document 30 40 947 C2 an upsetting press is known whose tools are designed such that the slab when subjected to a lateral upsetting action can neither bend upwardly nor downwardly. For this purpose securing plates are arranged above and below the slab. The upsetting tools for laterally upsetting the slab have U-shaped cutouts and surround the edge areas of the slab to a significant amount in order to prevent, together with the holding plates of the device, the bending of the slab during the upsetting process.
It is an object of the present invention to improve the upsetting tool of a slab upsetting press and to design it to be more universal with respect to applications in order to be able to upset the slab areally as well as in a width-calibrating fashion.
In accordance with the present invention, this is achieved in that the upsetting tool has plane upsetting surfaces as well as calibrating upsetting surfaces which are arranged above one another on the upsetting tool.
With this measure, a combination upsetting tool is provided which has two pressing positions on one and the same tool so that even during passage of a slab through the upsetting press it is possible to switch from a calibrating upsetting to an areal (surface) upsetting or vice versa. Depending on material and temperature of the slab, this has advantages with respect to the flow behavior of the material toward the slab center so that the so-called dog bone cross-sections can be substantially prevented and a substantially rectangular cross-sectional shape will be formed. Also, the formation of a tongue and fishtail on the respective end of the slab can be substantially prevented with the upsetting tool according to the present invention.
In an advantageous embodiment of the upsetting tool it is proposed that the slant angle xcex1 of the plane upsetting surfaces and of the calibrating surfaces correspond to one another. Since the slant angle on the upsetting tool inter alia determines the force requirement for lateral upsetting of the slab, it is advantageous to provide identical slant angles for the two pressing positions of the pressing tool.
In a further development of the inventive concept, it is proposed that the calibrating upsetting surfaces of the upsetting tool, viewed in cross-section, have substantially a U-shape that opens toward a longitudinal side of the slab. In this connection it is expedient that the U-shaped calibrating upsetting surface is comprised of a plane base surface and two leg surfaces that are positioned at a slant thereto and open outwardly. By means of these pressing surfaces, the dog bone formation on the longitudinal sides of the slab is avoided especially effectively.
In a preferred further development of the invention, it is proposed that the upsetting tool is connected with a tool holder of the upsetting press and can be moved vertically up and down in a direction parallel to the longitudinal side surface of the slab into an alternative pressing position relative to the slab in such a way that the slab can be reduced with regard to its width either with the plane upsetting surface or with the calibrating upsetting surface. By means of this measure, the combination upsetting tool with its two pressing positions is usable especially quickly and universally. Moreover, it is possible to optimally reduce the slab width during one pass through the upsetting press by means of two different pressing surfaces.